Tyson Gay knows he will have to raise his game at the World Championships in Beijing in September if he is to beat Jason Gatlin in the 100 metres.

Gatlin showed his power on Thursday at the latest Diamond League meeting in Lausanne, winning in a time of 9.75seconds - the second fastest time of the year - from Asafa Powell and Gay to send a warning to his sprint rivals.

"This guy has improved," said Gay. "He has improved his top end speed also, so it's going to be tough to get him. But I just have to work on my race.

"He's polished, he's sharp, he's doing great right now. Like I said, it's not going to be easy. He has a lot of confidence and he's on a roll right now, so I just have to worry about my race."

Powell " who just held off Gay to finish second behind Gatlin " agrees that he will have to do something special in China later this year if he is to take gold away from his rival.

He added: "I'm feeling very good. I'm healthy. I didn't run like I should.

"The first part of my race wasn't all that good. I kind of lost track, because I didn't want him [Gatlin] to get ahead of me, so I lost track a little bit and I finished the race healthy.

"That's the best of Justin, he's very consistent at 9.75, so it's just up to me to work my way through and surpass that.